What is an oral glucose tolerance test (OGTT)?

Your OGTT result

For a 75 gram test in non-pregnant adults, MedlinePlus lists these two-hour values:

• below 140 mg/dL: normal
• 140 to 199 mg/dL: impaired glucose tolerance (prediabetes)
• 200 mg/dL or more: diabetes

Pregnancy uses different cut-offs, and ranges may vary slightly by lab.

What an OGTT tells your doctor

It is more sensitive than a fasting test alone, so it can pick up early trouble with sugar that other tests miss.

Doctors often use it:

• for women with PCOS
• during pregnancy, to check for gestational diabetes
• when other sugar results are borderline

A high two-hour value means your body is struggling to clear sugar from the blood.

On the day of the test

On the day, follow your lab's instructions:

• fast for at least eight hours
• sit quietly during the test
• avoid walking about or smoking, as these can change the result

Over the longer term, the same habits that steady everyday sugar help here too:

• meals built around dal, vegetables and whole grains
• fewer sweets and refined flours
• regular walking
• enough sleep
• gradual weight loss if needed

Talk to your doctor before changing any medicine.